Marcus Singer

Factors Which Control the Staining of Tissue Sections with Acid and Basic Dyes

Publisher Summary There are numerous and diverse factors that profoundly influence the dye uptake of proteins of cells and tissues. The variable that affects dyeing most profoundly is pH. Other factors of importance are ionic strength of the dye medium, concentration of dye, nature and affinity of the dye, fixation and other chemical modification of the protein, temperature, diffusion, rate of staining, and the chemical and physical characteristics of the protein. Acid (anionic) and basic (cationic) dyes are aromatic compounds of various complexities containing a water-solubilizing group, which in the case of acid dyes is frequently a sulfonic radical (SO 3 H) but which also may be a carboxyl or hydroxyl group. The profound influence that pH exerts on staining reflects in large part the sensitivity of the dissociation characteristics of proteins to alterations in the solution environment. The ability of proteins to take up acid or basic dye according to the acidity of the environment is an expression of the amphoteric properties and of the charge on the dye ion.

The Increased Basophilia of Tissue Proteins After Oxidation with Periodic Acid

Oxidation by periodic acid (a 1% aqueous solution for 1 hour at 37°C.) greatly enhances the basophilic staining normally present in the keratinized portions of epidermis and hair. It also induces strong basophilia in purified fibrin and in the cytoplasm of smooth and striated muscle fibers, endothelium and the cells of the pancreatic islets and acini Proof is offered that this observed basophilia differs from that of either acid mucopolysaccharides or nucleoproteins. The conclusion is reached that, besides revealing polysaccharides occurring in tissue sections, periodic acid also brings about the formation of strongly acid, basophilic groups. These acid groups have not been identified, but since they may be formed most readily in regions of high sulfur content, it is suggested that sulfide and sulfhydryl groups may be oxidized to the corresponding sulfonic acids which could account for the observed characteristics of the basophilic substances.

Induction of Regeneration of Body Parts in the Lizard, Anolis.

Summary The amputated hindlimb of the lizard, Anolis carolinensis, incapable of regenerating, may be caused to grow by augmenting the nervous supply of the wound surface with additional nerves deviated from the opposite hindlimb. In addition, deviation of hindlimb nerves into the tail region also induced growth responses. The conclusion is drawn that the reptilian nerve does have the growth-evoking quality exhibited so well by nerves in lower forms and that reptilian body parts do have the power to regrow provided, among other conditions, that the nerve stimulus is quantitatively adequate. I am grateful to Paula di Santo Bensadoun for drawings in Figs. 1, 2, and 4 and to E. Bailey for Fig. 3.

Induction of Regeneration of Forelimb of the Frog by Augmentation of the Nerve Supply.

Summary The ability of the amputated forelimb of the tadpole to regenerate declines and in most cases is lost completely at the time of metamorphosis. However, .the present report shows that regeneration can be evoked experimentally in the adult frog if the number of nerve fibers available at the amputation surface of the forelimb is augmented by deviation of the sciatic nerve from the hindlimb. The theoretical considerations which led to these experiments emerged from the study of the influence of quantity of nerve fibers in regeneration in salamanders and are discussed here.

Apparatus for Continuous Infusion of Microvolumes of Solution into Organs and Tissues.

Summary An apparatus is described for infusion of small volumes of test solutions directly into tissues and organs. In more than 3000 successful infusions of the early regenerating limb of salamanders, volumes of 0.001 cc per hour have been introduced for periods of 5 or more hours. The apparatus consists of an advancing bar which is driven forward by a screw shaft attached to a clock motor. The advancing bar presses against the plungers of small syringes forcing fluid into fine polyethylene tubing and thence through a glass capillary needle into the tissues.

The acetylcholine content of the normal forelimb regenerate of the adult newt, Triturus

Abstract The acetylcholine content of normal and regenerating tissues of the forelimb of the newt was assayed by means of the clam heart. The results show that during the formative phases, during growth, and during differentiation there is a substantial amount of acetylcholine present in the regenerate. Indeed, the results suggest that within a few days of amputation, before the time of first appearance of mesenchymatous cells, the amount of acetylcholine probably resembles that of normal tissue. The studies also show that during the time when the nerve exerts its greatest influence upon growth, the acetylcholine content rises to a level high above that of normal tissue. Then, as differentiation sets in, it drops and eventually reaches the level of normal tissue. The significance of these variations is discussed in terms of the role of the nerve in regeneration of the limb; and the content of acetylcholine in the regenerate and embryo is compared.